That is, can a code generated by a computer act as a legally binding signature for a contractual agreement in halacha? If so, is this true even if the code is not certified by a trusted authorized third party that verifies the identity of the signer with the code? If yes, then is this true even if there is no physical handwritten signature involved in the process of authorizing the certification (such as simply checking a box)? If all of the above are true then can this type of signature be used to make a significant purchase, like buying real estate?